I have used this cooler with a copper pipe manifold for over a year and I fly sparge with the lid hinged. My average efficiency is around 75%. If the manifold is properly set up, then you won't get channeling. I think that is the whole point of a manifold, not just a drain hole at one end. Just my two cents worth.

because the cooler is long and the drain is at one end. In theory you will have more flow at the end when the drain is and less or maybe no flow at the opposite end. So you rinse the crap out of the grain near the drain and the opposite end doesn't get rinsed at all. This the theory behind a false bottom or a pipe manifold. They encourage more even flow. The ideal mash tun for fly sparge is round, has a fairly deep grain bed, has a false bottom and has the drain in the center.

If you have a manifold, why does it even matter what shape it is? Once the wort enters the manifold, the distance it travels inside is a moot point.

If you have a manifold, why does it even matter what shape it is? Once the wort enters the manifold, the distance it travels inside is a moot point.

From what I've read round coolers are better for fly sparging mainly because they are tall, so the grain bed is deeper, and because it is easier to install a false bottom.

With the good old sliding tee arrangement you could test whether it makes a any difference having the drain connected to the middle of the manifold or one end. It might make a tiny improvement. Fly sparging is a black art so who knows.

I have used this cooler with a copper pipe manifold for over a year and I fly sparge with the lid hinged. My average efficiency is around 75%. If the manifold is properly set up, then you won't get channeling. I think that is the whole point of a manifold, not just a drain hole at one end. Just my two cents worth.

I purchased this cooler and ordered the hardware. This will be my first All Grain batch.

Do you guys pre-heat this cooler with hot water, then dump it out before mashing in? If so do you then heat your strike water to your desired mash temp? The recipe I'm trying first calls for a mash temp of 154. I'm wondering if I should pre-heat this cooler or if I should just heat the water to 164 or something like that and not pre-heat the cooler.

Also, this recipe has 12 pounds of grain. I'm going to keep doing 5 gallon batches for a while until I have my process dialed on this new system. It calls for a "mash thickness" of 1.5. I assume that is inches?? Do I need to worry about this? I'm batch sparging, and since this cooler is pretty large for 5 gallon batches, I don't know how I would go about this.